Visceral leishmaniasis in Omani children: a review

Pathological roles of macrophages in Leishmania infections

Macrophages are the major host cells for Leishmania parasites, and determine the fate of infection by either limiting or allowing growth of the parasites, resulting in development or control of leishmaniasis, respectively. They also play important roles in causing pathological outcomes during Leishmania infection. The pathophysiology is complex and include a wide variety of molecular and cellular responses including enhancement of inflammatory responses by releasing cytokines, causing damages to surrounding cells by reactive oxygen species, or disordered phagocytosis of other cells. It is of note that disease severity in leishmaniasis sometimes does not correlate with parasite burdens, indicating that pathological roles of macrophages are not necessarily linked to their parasite-killing activities that are often defined by M1/M2 status. Here, we review the roles of macrophages in leishmaniasis with a focus on their pathological mechanisms in disease development.

Assessment of liver function test and associated factors among visceral leishmaniasis patients attending university of gondar leishmaniasis research and treatment center, Northwest Ethiopia

BACKGROUND

Visceral leishmaniasis (VL) is one of the major public health burden, mainly distributed throughout tropical and subtropical regions of the world. Among the Sub-Saharan African countries, Ethiopia is the second most affected country with VL. An Alteration of liver function is a typical manifestation of the disease.

OBJECTIVE

The purpose of conducting this study was to assess liver function tests and associated risk factors among VL patients at Leishmaniasis Research and Treatment Center of University of Gondar Comprehensive Specialized Hospital, North West Ethiopia.

METHOD

Hospital based comparative cross-sectional study design was conducted. A total of 102 study participants were involved in this study. Newly diagnosed VL patients who were attended at Leishmaniasis Research and Treatment Center of University of Gondar Comprehensive Specialized Hospital from 21st February 2020 to 30th September 2020 were included under case group category. On the other hand, age-sex matched apparently healthy study subjects were categorized as control group. Written consent was obtained willingness of patients to participate after ethical clearance was obtained from the Institutional Review Board of School of Medicine, University of Gondar. After overnight fasting, 5ml venous blood was drawn from both VL patients and controls to evaluate liver function tests, including AST, ALT, total bilirubin, albumin, and total protein. Thus, senior health professionals (laboratory technologist) investigate the results using Cobas Integra 400 Plus clinical chemistry analyzer. Data was entered into Epi-data version 4.6 and exported to STATA 14 for analysis of liver function tests and associated risk factors.

RESULT

The result of this study showed that significant mean difference was exhibited in aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, serum albumin, and total protein level among VL patients and controls. It showed that there was a statistically significant elevation in the level of AST, ALT, and total bilirubin among cases as compared to control. The serum AST level was significantly (p<0.001) elevated among cases as compared to controls. Serum ALT was significantly (p<0.001) elevated among cases compared to controls. Additionally, the total serum bilirubin level was significantly increased (P<0.001) among cases as compared to controls. There was a statistically significant (P<0.001) reduction of serum albumin level among VL patients as compared to controls. Similarly, serum total protein was significantly (P<0.001) reduced in VL patients than control groups.

CONCLUSION

There were significantly higher mean levels of serum AST, ALT, and total bilirubin among VL patients as compared to controls. On the other hand, VL patients showed significantly lowered level of albumin and total protein as compared to controls.

Hepatomegaly Associated with Non-Obstructive Sinusoidal Dilation in Experimental Visceral Leishmaniasis

Visceral leishmaniasis (VL) is the most severe form of leishmaniasis caused by protozoan parasites of the genus Leishmania. Hepatomegaly is one of the most frequent clinical manifestations of VL, whereas immunopathology of the symptom has not been well investigated. Using our chronic model of experimental VL, we examined the influence of Leishmania donovani infection on the liver by clinical, histological, and biochemical analyses. The infected mice showed increased liver weight 24 weeks post-infection. Although an increase in serum ALT and inflammatory cell accumulation were observed in the livers of infected mice, no apparent parenchymal necrosis or fibrosis was observed. Tissue water content analyses demonstrated that increased liver weight was predominantly due to an increase in water weight. Together with the finding of hepatic sinusoidal dilation, these results suggested that edema associated with sinusoidal dilation causes hepatomegaly in L. donovani infection. Immunostaining of platelets and erythrocytes showed no thrombus formation or damage to the sinusoidal endothelium in the liver of infected mice. Taken together, these results suggest that hepatomegaly during experimental VL is caused by non-obstructive sinusoidal dilation.

Zoonotic Diseases in Oman: Successes, Challenges, and Future Directions

Objective: This article describes the situation analysis of endemic and emerging zoonoses, and includes prevention and control of zoonoses in Oman. It also suggests possible recommendations toward elimination and risk reduction of emerging zoonoses. Methods: Epidemiologic information has been drawn from official to assess the situation. There has been significant progress in reducing the risk of brucellosis, Middle East Respiratory Syndrome Coronavirus, Crimean-Congo hemorrhagic fever, and cutaneous leishmaniasis. Rabies, West Nile fever, Q fever, and cystic hydatid disease have been confined to wildlife or livestock. Results: There is an increasing threat of emerging and re-emerging zoonoses in Oman due to globalization of travel and trade, development activities, and impact of climate change and vector bionomics. Prevention, control, and subsequent elimination of zoonoses on a sustainable basis shall not be possible without intersectoral collaboration between the human and animal health sectors. There are challenges for establishing such strong collaboration and coordination mechanisms in Oman. Institutional and cultural barriers, data and resource sharing, and national capability for rapid and effective investigation of zoonotic infections and emerging zoonoses in humans and animal reservoirs are among others. Conclusions: In the light of achievements made on the prevention and control of zoonoses in Oman during the past decades, priority zoonoses should be identified for elimination, and continuous efforts should be made to further strengthen a holistic multidisciplinary and multisectorial approach for controlling zoonoses at source. Pivotal interventions would include urgent adoption of "One Health" strategic approach as well as establishment of a robust, integrated surveillance system with a strong laboratory investigation capacity to eliminate priority zoonoses and minimize the risk of entry, establishment, and spread of emerging zoonoses in Oman.

Prevalence, severity, and pathogeneses of anemia in visceral leishmaniasis

Anemia is a typical symptom during visceral leishmaniasis (VL). We performed a systematic analysis of the literature on anemia in VL to understand the prevalence, severity, and possible mechanisms. Anemia is very common in VL patients with an overall prevalence higher than 90 %. The degree of anemia in VL is moderate to severe (hemoglobin level ∼7.5 g/dl), and the status can be recovered by treatment with antileishmanial drugs within a certain period of time. Possible pathogeneses of anemia in VL based on clinical observations included anti-RBC antibodies, dysfunction in erythropoiesis, and hemophagocytosis in the bone marrow or spleen, while hemolysis is a more likely cause than dyserythropoiesis. In hamsters with experimental VL, hemophagocytosis induced by immune complex and changes on erythrocyte membrane is speculated as the pathogenesis for anemia. In contrast, our recent study on murine VL indicated that hemophagocytosis contributes to anemia in contrast to lower contribution of anti-RBC antibodies or dysfunction in erythropoiesis. Together, hemophagocytosis is most likely associated with anemia in VL, and elucidation of the immunological mechanisms may lead to development of novel interventions to manage the symptom.